1. Field of the Invention
This invention generally relates to dual-path optical systems and, more particularly, to dual-path optical systems that are pseudoscopic.
2. Description of the Prior Art
Dual-path optical systems are well-known in the optical arts and include two general classes of devices referred to as binocular and biocular. Binocular devices include any instrument in which both eyes are used to view an image to achieve stereoscopic effects or to facilitate observation. They are characterized by having two mechanically linked but optically uncoupled optical paths to provide separate twin inputs and outputs to the visual system. True stereoscopic perspective is, more or less, commonly present in such devices so that an observer's eyes see objects from slightly different points of view to permit the perception of depth and dimension. Prism binoculars, binocular magnifiers, and binocular microscopes are examples of such systems.
The most common biocular devices are those which are designed so that both eyes view an object through a single exit pupil, i.e., there is a single input and a twin output. They are different from binocular devices in that they contain elements that are common to both eyes. Examples of such devices include gunsights and general purpose night vision goggles such as those described in U.S. Pat. No. 4,392,710.
Other types of biocular systems provide for two eye viewing through different parts of different elements which themselves are arranged along a single optical axis. With such systems, images typically get inverted and reverted, so objects must be manipulated to provide normal image orientation to an observer.
In both binocular and biocular devices proper image orientation and stereoscopic perspective is normally desired and achieved through the use of elaborate erecting systems in conjunction with suitable objectives and eyepieces. For example, the erecting system commonly used in standard binoculars to achieve the stereoscopic effect and proper image orientation comprises double Porro prisms in conjunction with modified Erfle eyepieces and achromatic doublet objectives. Such systems are more or less expensive and difficult to fabricate because of the tolerances required in manufacture and alignment of the various components, especially the prisms.
Proper image orientation and stereoscopic perspective are not always the design goal with such systems. For certain applications such as in the study of the visual perceptual system, it is desirable to provide reversed left and right, or pseudoscopic, perspectives. However, such systems as the one evidenced by U.S. Pat. No. 3,655,264 issued on Apr. 11, 1972 to Theodore C. Pickett and entitled "BINOCULAR VIEWING DEVICE" for the same reasons appear to be no less complex and inexpensive than the typical stereoscopic counterpart.
Inexpensive binoculars are also known in the art. These typically comprise a pair of terrestrial telescopes, usually of Galilean form, whose elements are usually injection molded of optical plastics and aligned in plastic housings for purposes of reducing costs. Obviously, such systems suffer in performance and utility.
In view of the above, it is a primary object of the present invention to provide a dual-path optical system made of low-cost components that may be easily assembled and aligned.
It is another object of the present invention to provide a low-cost pseudoscopic dual-path optical system.
It is yet another object of the present invention to provide a low-cost pseudoscopic binocular system in which any differences in left and right image perspectives are not apparent to the user.
It is yet another object of the present invention to provide a low-cost monocular optical system in which a coupled plane mirror system is employed as an erecting system.
Other objects of the invention will be apparent and will appear hereinafter in the following detailed description.